Tube connection, e. g. for a ladder

ABSTRACT

The invention concerns a process for connecting two mutually perpendicular tubes of different diameters by anchoring the end of the smaller tube in a bore in the mantle surface of the larger tube, particularly for connecting rungs and stiles, of a ladder, and a ladder so made. A plug of frusto-conical shape is introduced with its narrower end into the smaller tube the end of which, together with the plug, is pressed through the bore against the inner wall of the thicker tube such that the edge of smaller tube within the bore is deformed against the bore edge by the plug.

United States Patent [191 Zenhiiusern [111 3,881,572 [4 1 May 6,1975

[ TUBE CONNECTION, E. G. FOR A LADDER [76] Inventor: HeinrichZenh'tiusern,

Birmensdorferstrasse 134, 8902, Urdorf, Switzerland [22] Filed: Aug. 20,I973 [2!] Appl. No.: 389,662

[30] Foreign Application Priority Data Aug. 25, I972 Switzerland12703/72 [52] US. Cl. 182/228 [51] Int. Cl. E066 7/50 [58] Field ofSearch l82/228, 194; 403/263,

[56] References Cited UNITED STATES PATENTS 3,073,627 l/l963 Ritter403/248 3,327,385 6/1967 Shaver 182/228 Primary ExaminerReinaldo P.Machado Attorney, Agent, or Firm-Abraham A. Saffitz 57] ABSTRACT Theinvention concerns a process for connecting two mutually perpendiculartubes of different diameters by anchoring the end of the smaller tube ina bore in the mantle surface of the larger tube, particularly forconnecting rungs and stiles, of a ladder, and a ladder so made. A plugof frusto-conical shape is introduced with its narrower end into thesmaller tube the end of which, together with the plug, is pressedthrough the bore against the inner wall of the thicker tube such thatthe edge of smaller tube within the bore is deformed against the boreedge by the plug.

2 Claims, 4 Drawing Figures PATENTEDHAY 61975 SHEET 10F 2 r/ j /v p r aTUBE CONNECTION, E. G. FOR A LADDER ular tubular pieces with differentdiameters by anchoring the tube end of the thinner tube piece in acorresponding bore in the mantle surface of the thicker tube piece,particularly for connecting ladder rungs with ladder stiles. Theinvention also relates to a ladder made by the process.

There are known tube connections, or rather ladders, wherein the stilesare provided with bores in the mantle surface thereof into which boresthe rungs are pressed, welded, flanged or riveted. All there processesare intricate, time-consuming and, in many respects, disadvantageous. Inwelding, stresses arise at the weld locations, whereby a weakening ofthe construction results. The connections may easily become loose andcracks often arise which can only be detected later and lead toaccidents. Great demands are made on those ladders which find use insewage pits and canals and which are there particularly exposed tocorrosion.

It is an aim of the invention to propose to process which permits asimple and very easily achievable connection of tube pieces, whichconnection is absolutely water-proof, does not loosen but rather remainspractically non-detachable.

The proposed process consists in that a plug which widens conically isintroduced with its narrow end into the end of the thinner tube and thetube piece end together with the plug are pressed through the bore inthe mantle surface of the thicker tube piece against the inner wall ofthe latter opposite the bore such that the edge of tube piece within thebore is spread out and compressed against the bore edge due to thepenetration thereinto of the plug, whereby to form a waterproof andnon-detachable connection.

Preferably, at the inner wall of the thicker tube piece, at least whereit is opposite the bore in the mantle surface, a stop in the form of aweb is arranged against which the free end of the plug is pressed.According to a preferred embodiment through the use of additionallateral webs the pressed-in tube end will be particularly well blockedin.

A ladder made by the process has conical plugs pressed into the rungends, which plugs come to bear against a web which extends along theinner wall of the ladder stile opposite the bores in the mantle surfaceof the stile which serve for receiving the rungs.

There may also be a plurality of parallel webs present which arearranged and distributed around the periphery of the inner wall of thetube in the region of the mantle bores.

The accompanying drawing illustrate exemplary embodiments of thesubject-matter of the invention and show:

FIG. I is a horizontal section of a tube connection,

FIG. 2 is the same connection in vertical section along the line ll ofFIG. 1,

FIG. 3 is a horizontal section of a variant of FIG. I, and

FIG. 4 is a detail view.

FIGS. 1 and 2 show the connection of two mutually perpendicularlyextending tube pieces I and 2, where one ofthe tubes l has a greaterdiameter than the other tube 2. The tube 1 is provided with a bore 3 inits mantle surface through which the end of tube 2 is to be introducedand anchored. To this end, a frusto-conical plug 4, e.g. of hardplastics material, is provided the small, possibly ribbed, end 5 ofwhich is introduced into the end of the tube 2. Next, the tube 2 ispressed into the bore 3, whereby the projecting end 6 of the plug 4comes to bear either directly against the inner wall of the pipe 1 or,as shown in FIG. 1, abuts against a web 7 which is located at the innerwall opposite the bore 3 in the mantle surface of the tube 1. When thetube 2 is pressed in, the frusto-conical plug 4 spreads the edge of thetube 2 apart and compresses it against the edge of the bore so that awaterproof and non-detachable connection is formed. Simultaneously thetube 2 is closed off inside and outside and the penetration of moistureis prevented. Expediently, the rungs made from the tubes 2 areprestressed, whereby an torsional load that may arise is compensated.

FIG. 3 illustrates a further developed exemplary embodiment of the tubeconnection. The larger tube piece is designated here with 8 and has abore 9 into which the smaller tube piece 10 is to be set. Serving toanchor the latter, a plug 11 is again used, which is shown in detail inFIG. 4.

This plug 11 is essentially arranged in five sections. An end section 12is cylindrical and of somewhat smaller cross-section than the internalcross-section of the tube 10 to be secured. This section 12 serves forguiding the plug I1 and holding it tightly when it is engaged into thetube 10. Next a frusto'conical part 13 is present, the smallestcross-section of which corresponds to that of the section 12, while itsgreatest crosssection exceeds the internal cross-section of the tube 10.This part 13 has the task of widening the end of the tube 10 when thelatter is pressed in.

A short cylindrical part 14, adjoining the frustoconical part 13,changes into a wider frusto-conical part 15 which has the task ofspreading apart the edge of the tube 10 in the final phase of thepressing-in. Finally, the end part 16 lies with its end face against theinside of the web 17 arranged on the inside of the tube (see FIG. 3).

It is furthermore advantageous if additional webs 18 are arrangedlaterally of and parallel with the web 17, which webs provide additionalresistance during the introduction of the tube end 10 to the plug II andcause a still better upsetting or compression of the edge of the tube 2.[n this way a ladder made of prefabricated elements may very quickly andsimply be assembled together, wherein the non-detachable connectionsbetween stile and rungs are absolutely waterproof and remain veryresistant to external chemical and physical influences. Advantageouslythe free ends of the tubes 1 or 8 forming the stiles are closed off withclosure plates so that the interior of the tubes is protected againstcorrosion. The webs utilised serve additionally as stabilisers, wherebythe bending resistance of the ladders is increased. The weakening of thetubes 1 or 8 due to the bore 3 or 9 is compensated by the webs 7 or 17and I8 and by the prestressing of the rungs.

l claim as my invention:

1. A tube connection comprising a first tube, a second tubesubstantially perpendicular to the first tube, the tubes havingdifferent cross-sections, a bore formed in the second tube for receivingthe first tube, a connecting member a part of which is received in theopen end of the first tube and the remainder of which abuts, directly orindirectly against the inner wall of the second tube, wherein theconnecting member comprises a first, cylindrical portion, a second,frusto-conical portion, a third, cylindrical portion, a fourth,frustoconical portion, and a fifth, cylindrical portion, the firstportion being of greater diameter than the fifih portion and the secondportion, is of greater maximum diameter than the internal diameter ofthe first tube to assist in deforming the end of the latter against theedge of the bore in the second tube and the inner wall of the secondtube.

2. A tube connection, particularly suitable for connecting ladder rungswith ladder stiles, consisting essentially of:

a first tube which forms the rungs of the ladder;

a second tube having a larger diameter than the first which forms therail of the ladder;

a substantially frusto-conical plug having a projecting annular edge,pressed partly into the end of said first tube for each connection;

said first tube receiving a bore of said second tube;

said bore of said second tube receiving said end of said first tube andalso said plug;

a plurality of mutually parallel webs which are arranged and distributedalong the periphery of the inner wall of said second tube to serve asstops; and,

said end of said first tube being deformed against the edge of the boreby the plug to bear against said stop to thereby press the plug againstthe inner wall of the second tube.

a: 1: a s

1. A tube connection comprising a first tube, a second tubesubstantially perpendicular to the first tube, the tubes havingdifferent cross-sections, a bore formed in the second tube for receivingthe first tube, a connecting member a part of which is received in theopen end of the first tube and the remainder of which abuts, directly orindirectly against the inner wall of the second tube, wherein theconnecting member comprises a first, cylindrical portion, a second,frusto-conical portion, a third, cylindrical portion, a fourth,frusto-conical portion, and a fifth, cylindrical portion, the firstportIon being of greater diameter than the fifth portion, and the secondportion, is of greater maximum diameter than the internal diameter ofthe first tube to assist in deforming the end of the latter against theedge of the bore in the second tube and the inner wall of the secondtube.
 2. A tube connection, particularly suitable for connecting ladderrungs with ladder stiles, consisting essentially of: a first tube whichforms the rungs of the ladder; a second tube having a larger diameterthan the first which forms the rail of the ladder; a substantiallyfrusto-conical plug having a projecting annular edge, pressed partlyinto the end of said first tube for each connection; said first tubereceiving a bore of said second tube; said bore of said second tubereceiving said end of said first tube and also said plug; a plurality ofmutually parallel webs which are arranged and distributed along theperiphery of the inner wall of said second tube to serve as stops; and,said end of said first tube being deformed against the edge of the boreby the plug to bear against said stop to thereby press the plug againstthe inner wall of the second tube.